From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id D7DF0C2D0DB for ; Wed, 22 Jan 2020 13:53:57 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A0A712087E for ; Wed, 22 Jan 2020 13:53:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579701237; bh=kfkM0OO/6qoQn7WkKrjUokHyAGYTRZrspwgC6wX5VVQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=0tVrBmEJd7df8FkQ0C9T/M87N/p6LD5rZV1lenCmnf3XPyolRlfXRpcp2imMDhyJP koNybAeCCnZkZwZY5RMznP2HDs8aR/TMzVCaNlDbNo1+t531BPgu0kEWSnrDFUhqRR Yj60hgMQrUBwrF2CPnL/cjC0diL3nv0UFk5g0s6A= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729147AbgAVNx4 (ORCPT ); Wed, 22 Jan 2020 08:53:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:42438 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725805AbgAVNx4 (ORCPT ); Wed, 22 Jan 2020 08:53:56 -0500 Received: from localhost (unknown [84.241.205.26]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 957192087E; Wed, 22 Jan 2020 13:53:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1579701235; bh=kfkM0OO/6qoQn7WkKrjUokHyAGYTRZrspwgC6wX5VVQ=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=MyI0o4v0TD/rNBFJ2TTdFK7YlKkZteCmQRydXXqEJowWp5rgmneOdW1I6KscdROSu MQhisH+peq6U991ykurVUtaNWiglZHGOhEWVm2QkkzXNWJPzrtepAbnnN5N6pu/XDA fcpblOF/AfjSW86ttf3Lt6prXWUugZ8fPJhF+0l8= Date: Wed, 22 Jan 2020 14:53:52 +0100 From: Greg Kroah-Hartman To: Jason Baron Cc: Will Deacon , linux-kernel@vger.kernel.org, kernel-team@android.com Subject: [PATCH v2] dynamic_debug: allow to work if debugfs is disabled Message-ID: <20200122135352.GA9458@kroah.com> References: <20200122074343.GA2099098@kroah.com> <20200122080352.GA15354@willie-the-truck> <20200122081205.GA2227985@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200122081205.GA2227985@kroah.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org With the realization that having debugfs enabled on "production" systems is generally not a good idea, debugfs is being disabled from more and more platforms over time. However, the functionality of dynamic debugging still is needed at times, and since it relies on debugfs for its user api, having debugfs disabled also forces dynamic debug to be disabled. To get around this, move the "control" file for dynamic_debug to procfs IFF debugfs is disabled. This lets people turn on debugging as needed at runtime for individual driverfs and subsystems. Reported-by: many different companies Cc: Jason Baron Signed-off-by: Greg Kroah-Hartman --- v2: Fix up octal permissions and add procfs reference to the Kconfig entry, thanks to Will for the review. .../admin-guide/dynamic-debug-howto.rst | 3 +++ lib/Kconfig.debug | 7 ++++--- lib/dynamic_debug.c | 17 ++++++++++++++--- 3 files changed, 21 insertions(+), 6 deletions(-) diff --git a/Documentation/admin-guide/dynamic-debug-howto.rst b/Documentation/admin-guide/dynamic-debug-howto.rst index 252e5ef324e5..41f43a373a6a 100644 --- a/Documentation/admin-guide/dynamic-debug-howto.rst +++ b/Documentation/admin-guide/dynamic-debug-howto.rst @@ -54,6 +54,9 @@ If you make a mistake with the syntax, the write will fail thus:: /dynamic_debug/control -bash: echo: write error: Invalid argument +Note, for systems without 'debugfs' enabled, the control file can be +also found in ``/proc/dynamic_debug/control``. + Viewing Dynamic Debug Behaviour =============================== diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 5ffe144c9794..49980eb8c18e 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -98,7 +98,7 @@ config DYNAMIC_DEBUG bool "Enable dynamic printk() support" default n depends on PRINTK - depends on DEBUG_FS + depends on (DEBUG_FS || PROC_FS) help Compiles debug level messages into the kernel, which would not @@ -116,8 +116,9 @@ config DYNAMIC_DEBUG Usage: Dynamic debugging is controlled via the 'dynamic_debug/control' file, - which is contained in the 'debugfs' filesystem. Thus, the debugfs - filesystem must first be mounted before making use of this feature. + which is contained in the 'debugfs' filesystem or procfs if + debugfs is not present. Thus, the debugfs or procfs filesystem + must first be mounted before making use of this feature. We refer the control file as: /dynamic_debug/control. This file contains a list of the debug statements that can be enabled. The format for each line of the file is: diff --git a/lib/dynamic_debug.c b/lib/dynamic_debug.c index c60409138e13..0f1b26f10fb2 100644 --- a/lib/dynamic_debug.c +++ b/lib/dynamic_debug.c @@ -993,13 +993,24 @@ static __initdata int ddebug_init_success; static int __init dynamic_debug_init_debugfs(void) { - struct dentry *dir; + struct dentry *debugfs_dir; + struct proc_dir_entry *procfs_dir; if (!ddebug_init_success) return -ENODEV; - dir = debugfs_create_dir("dynamic_debug", NULL); - debugfs_create_file("control", 0644, dir, NULL, &ddebug_proc_fops); + /* Create the control file in debugfs if it is enabled */ + if (debugfs_initialized) { + debugfs_dir = debugfs_create_dir("dynamic_debug", NULL); + debugfs_create_file("control", 0644, debugfs_dir, NULL, + &ddebug_proc_fops); + return 0; + } + + /* No debugfs so put it in procfs instead */ + procfs_dir = proc_mkdir("dynamic_debug", NULL); + if (procfs_dir) + proc_create("control", 0644, procfs_dir, &ddebug_proc_fops); return 0; } -- 2.25.0